Dynamics of Harmonic Mode-Locking via Delayed Optical Feedback

Time-delayed optical feedback triggers rich nonlinear dynamics and has been intensively studied in systems such as semiconductor lasers, Kerr resonators, fiber lasers and optical parametric oscillators [1]–[3]. In particular, harmonic mode-locking (HML) via delayed optical feedback is promising for realizing low-noise, high repetition rate optical combs [4]. Most previous works have focused on optimizing steady-state operation, leaving the formation dynamics of HML under delayed optical feedback unexplored. In this work, we use real-time dispersive Fourier transform (DFT) technique to reveal these dynamics in a dissipative soliton fiber laser.